The invention is directed to a material application system for applying a material, such as salt, from a vehicle that is being driven to prevent the accumulation of snow on a road, for example.
A material application system of the above type is described in U.S. Pat. No. 4,373,668 to Forbes, et al. That system has a control panel 14 which, as shown in FIG. 3 of the patent, allows the operator of the vehicle to control certain functions. To that end, the control panel 14 includes an on/off switch 100, a spinner switch 62A that is used to adjust the speed of a spinner motor 26 that controls the spreading of granular material, a blast switch 110 to provide a relatively large application of granular material for a relatively short period of time, a switch 94 for increasing or decreasing the application rate of the granular material, and a mode switch 104. Other material application systems are described in U.S. Pat. Nos. 4,898,333 and 5,318,226 to Kime, et al.
Other prior art material application systems have been marketed by the Dickey-john Corporation, the assignee of this patent. One such system was provided with a single control module having a relatively small number, e.g. five, of multi-function keys. The control module was designed to be used by both a supervisor or programmer while the vehicle was not in operation and the driver of the vehicle when the material was being applied. Use of the control module by the programmer was intended to allow the programmer to program the material application system by entering a number of programming parameters to control various functions, such as granular application rates and/or liquid application rates.
Use of the control module by the driver during material application was intended to be more limited. The driver was only allowed to enter or modify certain operational parameters, such as an increase or decrease in material application rate, but not other operational parameters, referred to as "restricted" parameters. The material application system was provided with a password feature that allowed one with a password to enter or modify the restricted parameters. The entry of restricted parameters was controlled by providing programmers with passwords, but not providing drivers with passwords.